As Syria's new leaders take on the task of governing the country, world powers sent emissaries into the region on Thursday to begin trying to shape Syria’s future and their relations with the rebels who toppled Bashar al-Assad from the presidency.

The US secretary of state, Antony J. Blinken, met in Jordan with King Abdullah II and called it "a time of promise but also peril for Syria and its neighbours" before flying to Turkey to meet with President Recep Tayyip Erdogan.

Blinken said it was essential for Syria’s new government, led by a Sunni Islamist group that the US and others have called a terrorist organisation, to respect basic principles of human rights, including the protection of minorities, and to ensure that Syria "is not used as a base for terrorism by groups like the Islamic State".

He and Jake Sullivan, the US national security adviser, also delivered a message to Israel on Thursday, saying that its military presence in Syria, where it has taken control of a buffer zone along the Syrian-Israeli border, must be temporary. After the Assad government fell last weekend, Israel moved troops into the area and has carried out hundreds of airstrikes against the regime's military assets, saying it worried that extremists could exploit the power vacuum and seize abandoned weapons to attack Israeli territory.

"Israel is concerned that that vacuum could be filled by terrorists, by extremists, and so it moved forces into the buffer zone," Blinken told reporters in Jordan. "It has told us and told others that that's a temporary move, just to ensure, again, that this vacuum isn't filled by something bad."

Sullivan, after meeting in Israel with Prime Minister Benjamin Netanyahu, said that Israel's decision to send troops into the buffer zone was "logical and consistent" with its right to self-defence. But he said that the US had "every expectation" that Israel's military presence there would not be permanent.

Netanyahu said Israeli troops would remain in Syrian territory "temporarily", but did not provide a definite timeline for them to withdraw.

"The collapse of the Syrian regime created a vacuum on Israel's border and in the buffer zone," Netanyahu said in a statement. "Israel will not permit jihadi groups to fill that vacuum and threaten Israeli communities."

The rebel alliance that toppled al-Assad — whose family ruled for more than 50 years — was led by Hayat Tahrir al-Sham, a group once affiliated with al Qaida. The group’s leaders have said that they long ago abandoned the goal of global jihad and would work with all sects in Syria, but their agenda remains to be seen. Some analysts say the international community should remove the terrorist label from Hayat Tahrir al-Sham to enable countries to send aid to Syria and to exert influence over the group.

Turkey on Thursday appeared to be the first country to send a high-level official to Syria since the rebels seized control of the country.

Ibrahim Kalin, the head of Turkey’s national intelligence agency, known by its acronym MIT, was seen in Syria’s capital, Damascus, in footage shown on Turkish television. Kalin was shown leaving the Umayyad Mosque with armed personnel around him while dozens of Syrians recorded videos.

It was the same mosque that the leader of the Syrian rebel offensive, Ahmed al-Shara, formerly known by his nom de guerre, Abu Mohammad al-Golani, visited on Sunday to commemorate the success of the rebellion.

Turkey’s intelligence agency did not immediately comment on Kalin’s visit to Damascus. But the trip came as Blinken indicated concerns about new offensives by Turkish forces and a Turkish-backed militia against US-backed Kurdish forces in Syria's northeast, calling it "really important at this time that we're not sparking any additional conflicts." Turkey calls the Kurdish force a terrorist group, tied to rebel Kurds in Turkey.

The Kurdish-led civil administration in Syria's northeast said on Thursday that it had raised the Syrian independence flag above all government buildings, a largely symbolic move that it said affirmed "Syria’s unity and national identity" — apparently a signal to the new leaders in Damascus, who also have ties to Turkey.

New York Times News Service